1. Field of the Invention
The present invention relates to a system for supplying information from a database system or cable television system.
2. Background Art
In the information-oriented society of today, in addition to the existing terrestrial wave broadcasting, the use of satellite broadcasting via broadcasting satellites (BS) or communication satellites (CS) and the use cable television broadcasting (CATV) via coaxial cable or optical fiber cable are becoming widespread.
In CATV, which can distribute programs on several tens of channels at the same time, in addition to unscrambled general channels that viewers can view with a comprehensive subscription, scrambled pay channels such as those for motion pictures, sports, music, etc. are provided that cannot be viewed with the comprehensive subscription. To view these scrambled channels, it is necessary to subscribe for descrambling. However, since the period of subscription is typically about one month, it is not always possible to view the program by request at the desired time.
In order to view live sports programs, motion picture programs or music programs broadcast by scrambled satellite TV broadcasting or CATV channel, there is a system for "per program" viewing, in which a viewing time recorder is installed for each television set. Payment is made according to the record of the actual viewing time. However, such a system entails high cost and labor for control of the system and the collection of fees.
On the other hand, in the information-oriented society of today, a database system is becoming widespread, in which various types of data, independently stored by computers in the past, are utilized by connecting each computer via communication lines.
The information handled so far in such a database system is coded information that contains a relatively small amount of information or picture data, and that can be processed by computer. It is not possible to handle picture data such as that used for natural pictures or animation.
Under such circumstances, techniques have been developed to process picture signals, such as television signals, by compressing and expanding them using computers. As common standards for this purpose, there are JPEG (joint Photographic image coding Experts Group) standards for still pictures, H.261 standards for television conferencing, MPEG1 (Moving Picture image coding Experts Group 1) standards for storing pictures, and MPEG2 standards to cover the current television broadcasting and high definition television broadcasting. As the technique of the future, attention is now focused on "multi-media systems" for simultaneously handling various types of data processed by computers and picture data by digitizing picture signals.
This multi-media system is also incorporated into data communication, and is utilized as one of the data utilities in a database.
With the range of utilization of databases being expanded as described above, handling the charge for utilization of the data on databases becomes an important issue. To reliably charge a fee, it is necessary to provide a system wherein data cannot be used unless the user is a regular subscriber. The best means for this purpose is data encryption.
However, it is necessary to deliver a decrypting key to the user so that the regular user can decrypt the encrypted data and utilize it. Moreover, to ensure that the charging is performed more reliably, it is desirable to change the cryption key for each data selection. It is necessary to deliver a different decrypting key for each data selection. This leads to very troublesome procedures.
To solve the above problems, a system has been proposed by the present inventors in Japanese Patent Application 4-199942 (US-08/098415) and Japanese Patent Application 4-289074 (US08/143912). In these patent applications, it is provided that upon a request for viewing a scrambled program via public telephone line, a charging center transmits a viewing permit code for viewing the scrambled program to a data communication device, and charges and collects a fee. Upon receipt of the viewing permit code, a receiving device descrambles the program according to the viewing permit code, and allows the viewer to view the program. Also, for users utilizing encrypted data requested via public telephone lines, a charging center transmits a use permit code for using encrypted data to a data communication device, and charges and collects the fee. Upon receipt of the use permit code, a receiving device decrypts the encrypted data according to the use permit code, and allows the user to use the data. A device for this purpose is disclosed in Japanese Patent Application 4-276941 (US08/135634) by the present inventors.
In the following, an outline of the invention disclosed in the prior applications will be described.
FIG. 1 shows a charging system for CATV. This charging system comprises CATV station 1, a viewing permit code/charging control center ("control center 2"), communication device 3 and a tuner/decoder ("receiving device 4"). Dedicated communication line 5 is used for communication between CATV station 1 and control center 2. Communication line 6, such as public telephone line, connects control center 2 and communication device 3. Communication device 3 and receiving device 4 are connected by supply means 7, such as on-line or off-line means using flexible disk. CATV station 1 and receiving device 4 are connected by cable 8, such as coaxial cable or optical fiber cable.
CATV station 1 transmits a scrambled television signal to receiving device 4, and deposits a viewing permit code (a permit key), including data for descrambling the signal, in control center 2 in advance.
Control center 2 transmits a permit key to communication device 3 via communication line 6, in response to a viewer's request for viewing a scrambled television program made using communication device 3, and received across communication line 6. Control center 2 also charges a fee.
The viewer receives the permit key with communication device 3, and sends the permit key to receiving device 4 via supply means 7. Receiving device 4 descrambles the scrambled television program using the permit key. Thus, the viewer can view the requested television program.
In addition to the scrambled television program, the charging system is also applicable to data multiplex broadcasting, which is multiplexed and broadcast on a television broadcasting program or FM audio broadcasting program.
FIG. 2 is a block diagram of a charging system applied to data communication used in a database system.
The charging system comprises data communication host station 9 (such as the database system), control center 10, data communication device 11 and receiving device 12. Data communication host station 9 and control center 10 are connected by dedicated communication line 13. Control center 10 and communication device 11 are connected by communication line 14, e.g. a public telephone line. Communication device 11 and receiving device 12 are connected by appropriate means 15, e.g. direct on-line means or off-line means such as flexible disk. Data communication host station 9 and receiving device 12 are connected by communication line 16, e.g. a public telephone line.
Data communication host station 9 transmits encrypted data to receiving device 12 and deposits, in advance, a use permit code ("a permit key"), including data to be used for decrypting data, at control center 10.
Control center 10 transmits the permit key, in response to a user's request for use of the encrypted data, made via communication line 13 using the communication device 11. Control center 10 also charges a fee.
The user receives the permit key with communication device 11, and sends the permit key to receiving device 12 via supply means 15. Receiving device 12 decrypts the encrypted data using the permit key. Thus, the user who made the request is allowed to use the data.
With the system according to the invention described in the prior applications, it is possible to deliver and receive a permit key, and charge a fee at the same time and in a reliable manner.
However, the request for using data and the transmission of the permit key are executed via general communication lines such as public telephone lines. For this reason, the requests may not be processed adequately when there are too many requests at the same time.